Manufacture of dry-sealing envelopes



Feb. 23, 1943.

V. E. HEYWOOD MANUFACTURE OF DRY-SEALING ENVELOPES Filed July 15, 1940 5 Sheets-Sheet 1 Feb. 23, 1943.

V. E. HEYWOOD v MANUFACTURE OF DRY-SEALING ENVELOPES 5 Sheets-Sheet 2 Filed July 15, 1940' may 23, 9 v. E. HEYWOOD ,312,162

MANUFACTURE OF DRY-SEALING ENVELOPES Filed July 15, 1940 5 Sheets-Sheet 3 W '35 Z z JEW- Feb. 23, 1943. I V E HEYWOOD MANUFACTURE OF DRY-SEALING ENVELOPES Filed July 15, 1940 5 Sheets-Sheet 5 A nga-1 ,Jzzwn on WIZCYGIZfEl/ wad Patented Feb. 23, 1943 MANUFACTURE OF ENVELOP DRY- SEALING Vincent E. Heywood, Worcester, Mass., assignor to United States Envelope Company, Springfield, Mass., a corporation of Maine Application July 15, 1940, Serial No. 345,530

20 Claims.

- the envelope material while maintaining the adhesive coated areas out of engagement with each other.

Owing to the difficulty of of applying dry-sealing adhesive by the use of gumming dies usually employed in envelope machinery, it has heretofore been proposed to apply the adhesive with a wiping action to blanks arranged in stepped relation, for example as shown in Winkler and Dunnebier Patent No. 2,019,946, issued November 5, 1935. However, when dry-sealing adhesive is so applied to the exposed edges of blanks arranged instepped relation, special provision must bemade for separating the blanks to prevent adhesion to each other along their edges, and such separation-always involves the possibility of the adhesive stringing out, as separate coatings arepulled apart. According to the present invention, the problemsinvolved in the application of dry-sealing adhesive to diflerent and separated areas of envelope blanks, are successfully solved by utilizing the movements of a blank in dliferent planes to successively apply the adhesive with a wiping action to the different trailing edges of the blank. Following the separate applications of adhesive to each blank, blanks assembled in oflset relation are subjected to a. drying action from opposite sides, with the separate adhesive areas positively maintained in spaced relation,-

so that the possibility of stringing or edge sticking of adjacent blanks isentirely eliminated.

The above and otheradvantageous features of the invention will hereinafter more full .appear from the following description, with reference to the accompanying drawings. in which:

Fig. 1 is a view in side elevation of apparatus for carrying out the invention, with some parts in sections.

Fig. 2 is a view in front elevation of the parts shown in Fig. 1. I

Fig. 3 is a fragmentary plan view, on an enlarged scale, illustrating the positioning of a blank at an adhesive applying station.

Fig. 4 is a fragmentary view partly in section, along the line 4-4 of Fig. 3, and partly in elevation. I

Figs. 5, 6 and 7 are views similar to Fig. 4, showing the parts in different positions.

Fig. 8 is a plan view of the overlapped blanks shown in Fig. 7, as supported on the conveyor for drying.

Fig. 9 is a fragmentary plan view of an adhesive applying bar and its associated blank strippers.

Fig. 10 is a sectional view of the bar of Fig. 9, on an enlarged scale.

Fig. 11 is a plan view of the conveyor shown in Fig. 1, with other parts removed.

Fig. 12 is a sectional view along the line I2-I2 of Fig. 11 looking in the direction of the arrows.

Fig. 13 is a fragmentary sectional View along the line |3|3 of Fig. 12, looking in the direction of the arrows.

Fig. 14 is a fragmentary'and partly diagrammatic view illustrating the timing of the mechanism.

Referring first to Figs. 1 and 2, the apparatus consists of spaced side frame members I, be-

tween which is supported a stack of flat blanks 2, by means of pairs of posts 3 and 4 engaging in corners formed at the side flaps 2a of the stacked blanks. The lower posts 3 are carried by holders 5, longitudinally adjustable on brack ets 6, while the brackets Ii are adjustable on slides I carried by the frame members I at right angles to the holders 5.

Consequently, the posts 3 can be adjusted in two directions, so as to fit into the corners of difierent sizes of blanks, as indicated in dotted lines. The upper posts 4 are carried by holders ,8 adjustable in one direction on a cross member 9, so that the posts 4 can be adjusted to blank stacks of different widths, with the upper edge of the stack always centered with respect to a stop I0 extending slightly beneath the lowermost blank,.as shown in Fig. 1. The lower ends of the posts 3 terminate in stops II, slightly underlying opposite corners of the stack,-and followers l2 slidably mounted on the posts 3 above the stack,

exert a pressure tending to feed the stack toward the stops II, by reason of the connection of the inside of the posts 3 to a source of suction.

With the arrangement of parts described thus far, it is evident that the stack of blanks is supported at three points by the stops I II and I I, with I5 is adapted to be controlled by end lugs l6, ad-

justable within the trough so as to extend slightly within the margins of a blank, as also shown in Fig. 3.

The bar l3 also provides a narrow slit l1 disposed between the edge of the blank and the trough l5, and this slit communicates with a chamber l8 running the entire length of the trough l5, and connected to a suitable source of suction. When suction is applied to the lowermost blank through the slit H, the entire edge portion of the blank is held fiat against the bar, so that the blank makes a tight seal with the edges of the trough l5 between the end lugs l6. Consequently, when dry-sealing adhesive in liquid form is supplied to the trough I5 through a suitable supply pipe I9, the adhesive engages the lowermost blank along a zone slightly displaced from the lower edge of the blank. The suction applied to the blank through the slit l1 adjacent the trough, is sufiicient, however, to prevent leakage of the adhesive therefrom.

As best shown in Fig. l, a suction picker is mounted to turn with a shaft 2 I, and its free end is adapted to engage the upper edge of the lowermost blank adjacent the stop Hi. When suction is applied to the picker 20 and the latter is swung 'into the dotted line position, the upper end of the blank will be pulled away from the stop III to present its edge in the path of movement of a series of feed segments 22. The segments 22 are mounted in spaced relation on a shaft 23, and as -pose of which will later appear.

ameter of each segment 29 is less than the diam-' segments, and so facing toward a second adhesive applying bar 28, the function of which will later appear.

It is evident from Fig. 1 that the peripheral length of each segment 24 is considerably less than the length of the shortest blank being handled, and the apparatus-provides adjustable means for supporting each blank between the rear end of the segments 24 and the adhesive band A that is applied to the trailing end of the blank. To this end, guide segments 29 are mounted on the shaft 25 between the feed segments 24, with each segment 29 providing a groove 30, the pur- The outside dieter of the feeding portion of each segment 24, so that stripping fingers 3| can enter between the segments 29 and the second adhesive applying bar -28, as shown in Fig. 6.

The several guide segments 29 are connected together by a tie rod 32, so that all the segments can be turned in unison on the. shaft 25, and located in adjusted position by a set screw 33 passing through the hub of the center segment. a Thus, the segments 29 can be angularly adjusted with respect to the forward ends 24a of the feed segments, so as to provide a series of spaced supports for the blank being withdrawn, extending 'from the rear ends of the segments 24 to a point adjacent the band A of moist adhesive that has just been applied to the blank. This prevents buckling of the blank as it is carried around on the segments 24, with the adhesive band A facing the segments rotate in the direction of the arrow,

their advancing hooked ends 22a simultaneously engage the edge of the blank that has been previously separated from the stack by operation of the picker 26.

The segments 22 cooperate with a set of segments 24, mounted in spaced relation on a shaft 25 parallel to the shaft 23, as best shown in Fig. 2. The lower segments 24 are in vertical alinement with the segments 22, and their forward ends 24a are adapted to register with the forward ends 22a of segments 22 as the segments rotate in opposite directions. Therefore, the edge of the deflected blank will be seized between the segments, and the blank withdrawn from the stack. As this withdrawal occurs, the trailing edge of the lowermost blank 2 is drawn past the trough l5, so that dry-sealing adhesive is applied between the end lugs |6 clear up to the edge of the blank with a wiping action, while the next lowermost blank progressively comes into contact with the trough I5, in readiness for the next withdrawal.

Each segment 24 provides a slot 26 near its forward end 24a, and the slots of all the segments 24 are connected to a suitable source of suction by a cross-pipe 21, see Fig. 4. Therefore, as the leading edge of the blank being withdrawn leaves the bite between the segments 22 and 24, it is held on the segments 24 at the suction slots 26, and is wrapped around the segments 24 as the withdrawal progresses. As the leading edge of the withdrawn blank is carried around by the segments, the surface that was formerly uppermost in the stack is carried on th outside of the towards the segments 29, but entirely out of contact therewith.

As previously pointed out, a second adhesive applying bar 28 is located below the feed segfments 24, and as best shown in Figs. 3 and 4, is similar to the first bar l3, in providing an adhesive trough 34 and suction slit 35 with end lugs l6a determining the effective length of the trough 34. The bar 28 has a number of stripping fingers 3| mounted thereon, which fingers overhan both the suction slit 35 and the adhesive trough 34. The under side of eachfinger 3| is cut away to provide a shoulder 36 just beyond the edge of the suction slit 35, thereby leaving a space between the fingers and the edges of the adhesive trough 34, sufficient to admit at least two blanks, see Fig. 10.

When the feed segments 24 carrying the leading edge of a blank approach the adhesive bar 28 as shown in Fig. 4, it is evident that the fingers 3| lie nearer the axis of the shaft 25 than does the approaching edge of the blank 2. Therefore, as the forward ends 24a of the segments sweep over the bar 28, the fingers 3| enter between the blank and the peripheries of the guide segments 29 which, as previously pointed. out, are of less diameter than the big feed segments 24. This relation is shown diagrammatically in Fig. 6, wherein the different diameters of the segments 24 and 29 are shown with relation to the upper edge of the bar 28 andthe stripping fingers 3|.

Y24 and 29 continue their rotation free of the 'stripped blank, preparatory for the next blank feed, the trailing edge of the blank with the adhesive band A uppermost, swings downwardly toward a pair of spaced conveyor belts I! that are driven slowly in the direction of the arrow by a mechanism hereafterdescrlbed with reference to Fig. 11.

However, before the free end of this blank can reach'the plane of the belts 31, its trailing edge is prevented from further downward movement by a blade 38 extending over the space between the belts, as shown in Fig. 3. This blade 38 ls mounted on an arm 39 carrying one of a pair of rolls 40 adapted to be moved back and forth with respect to the belts 31. The opposite end of each arm 39 is mounted on a head 41, freely turnable on a pin 42 provided at the upper end of a lever 43 carried by a shaft 44 extending between the side frames I. The roll arm 39 is adjustable within the head 4! through the provision of a slot 39a, so that the extreme positions occupied by each roll 40 can be adjusted longitudinally of the cooperating belt 31, in order to operate on blanks of different lengths, see Fig. 1.

- Generally speaking, the setting of a roll 40 and its associated arm 38 is such that .when the roll 40 occupies the retracted position of Fig. 4, the blade 38 is clear of the falling end of an approaching blank as carried by the segments 24. However, as the segments move past the bar 2| to cause stripping of a blank, as previously described, the roll 40 moves to the position of Fig.-

5, wherein the blade 38 holds the end of the stripped blank above the belts 31, until the previously fed blank has been withdrawn from the bar 28 to cause the application of a second adhesive band B to the under side thereof that overlies the trough 34. In other words, as'each hesive band A is clear of the blank above. Thereblank that has just arrived, by cooperation between the rolls 40 and belts 31, as will next be described.

. from the segments 24, as shown in Fig. 5, and

its trailing end swings downwardly, as indicated I by the several dotted line positions, the blade 38 will be moved towards the bar 28 with the roll 40, to temporarily hold the end of the arriving blank away from the blank already on the belts 31.

Just after the arriving blank comes to rest against the stop shoulders 36, above the blank already in position, a series of clamping arms mounted on a cross rod 46, are moved downward slightly, as indicated ,by the arrow in Fig. 5. Each arm 45 carries a rubberblock 41, which engages the end of the uppermost blank between the fingers II, so as to exert a frictional force to oppose removal of the blank that is so engaged. The rod 48 is rotatably supported at its ends by brackets 48 carried by the frame members, see Fig. 9, and an arm 49 mounted on the rod 46 carries a roll Bl bearing on a cam 5| rotatable with the segment shaft 25. The cam II As best shown in Fig. 3, each roll 44 in its retracted position, is entirely clear of the side flaps 2a of the blank that is at the moment held at its end in engagement with the adhesive trough 34. Although the belts 31 are slowly moving away from the bar 24 underneath the flaps Ia, the suction along the slit 3! is quite suificient to hold the blank in position against the relatively slight pull exerted by the upper surfaces of the belts alone. However, as the rolls 40 move into the position of Fig. 5 and thereby engage the flaps 2a, the downward pressure of the rolls 4| is suflicient to cause the flaps 2a to be carried along by the belts 31. Therefore, the lower blank is withdrawn from beneath the upper blank which is held by the frictional blocks 41. on the clamping arms 45, and an adhesive band B is applied to the under side of the trailing end thereof as the blank clears the, trough 34, as indicated in Fig. 6. The upper blank thereupon takes the place of the blank being withdrawn, to keep the trough 34 covered at all times.

Since withdrawal of the lower blank from the bar 2. is followed by return movement of the rollers 4| to the right, the end of the blank that has Just been stripped is freed from the blade ll only after the advancing end of the underneath blank has reached a position where its adfore,-the upper blank flattens out on the lower blank, with their ends in offset relation, so. that the adhesive bands A are separated by a considerable space, which increases tothe extent shown in Fig. 6,. due to the continued pressure of the rolls 4! on the side flaps of the blank that has just beenremoved from the bar. By the time that the rolls 40 are again moved into the dotted line position to engage the flaps 2a of the second blank, athird blank has been stripped by the fingers II, so that withdrawal of the trailing end of the second blank from the trough 34 to apply adhesive thereto, is accompanied by gripping of the third blank by the clamping arms As the above described cycle of operations is repeated for each revolution of the segment shaft 25, an assembly of overlapped blanks accumulates on the belts'l'l, as indicated in Figs. 7 and 8, with the adhesive ,bands A and B uniformly spaced from each other, so that there is no possibility of anything coming in contact with the. moist adhesive while the blanks are supported between the belts 3!- by their overlapped side flaps. It is evident from Fig. 8, that by the time the fifth blank has joined-the assembly. .the side flaps 2a of the first blank. have come. under the first of a series of traction rolls 52, forming part of a conveyor which carries the assembled blanks into a heating zone. where the moist adhesive bands A and B on opposite sides of the assembly are subjected to a drying action. These rolls 52 are all so mounted as to'exert a pressure on the blank flaps as supported by the belts 31, so that the entire assembly of blanks moves along with the belts, with additional blanks being added to the assembly at intervals, each time that the rolls 40 move toward the adhesive bar 34 to en- Sage the flaps of a blank then held in contact with the adhesive in the trough 34.

As best shown in Fig. 1, the adhesive drying means consists of hoods ll, arranged above and below the belts l1 and traction rolls 52, with each hood providing a suitable heating element 54,

spaced from a reflecting surface 55. As a result. heat is directed towards the spaced adhesive bands A andB from both sides of the assembled blanks, so that the adhesive is dried to its proper dry-sealing condition before the performance of various folding and gumming operations involved in the conversion of the blanks into complete envelopes. Obviously, other drying means may be employed in cooperation with the conveyor, and

' if desired, the adhesive applying bar I3 at the stack can b omitted, and ordinary dextrine gum applied by the bar 28 to the seal flaps of blanks for ordinary envelopes.

As previously pointed out, the stack-supporting posts 3 and 4 are adjustable to accommodate blanks of different sizes, and the conveyor mechanism is correspondingly adjustable, so that the belts 1 can be set just the right distanceapart to support the side flaps of blanks of different widths. In Figs. 11, 12 and 13, the parts of the conveyor mechanism are shown separately from the adhesive applying devices previously described, and it is evident from Fig. 11, that the v conveyor can be made of any desired length, in

order to obtain the necessary drying of the adhesive as applied to the assembled blanks.

Referring now to Figs. 12 and 13, the upper portion of each belt 31 is supported by a rail 55 for the entire length of the conveyor, with the ends of the belt passing around pulleys 51 and 58. The rails 55 are mounted in parallel spaced relation on screw shafts 59 extending between the side frames 1, with each shaft 59 being oppositely threaded at 58 and 51, where it passes through bracket/s52 secured to the under side of a rail 55. Consequently, when a shaft 59 is turned, the rails 55 move toward or away from each'other, in order to vary the distance between the belts 31.

One shaft 59 extends beyond a frame member I, where it provides a slot 83 for receiving a suitable handle whereby it may be turned, and in order to insure movement of the rails 58 in exact parallel relation, the screw shafts 59 are connected together for turning in unison. As shown in Fig. 11, the shafts 59 are connected together by sprockets 54 and a chain 55, so that close adjustment of the spacing between the rails 55 can be obtained at any time, in order to accommodate the belts 31 to the exact distance between the side flaps 2a of the assembled blanks that are conveyed thereby, as previously described.

Each front belt pulley 51 is slidably keyed to a shaft 58 extending between the frame members I, and the shaft 85 is adapted to be continuously driven from the feed segment shaft through a train of reduction gearing 51, best shown in Fig. 2, so that the pu1leys 51 rotate at a much lower speed than do the segments 24. In order to cause the pulleys 51 and the belts 31 to move with the rails 55 when making an adjustment in the width of the conveyor, each rail bracket '52 provides wings 58 embracing a pulley 51, so that each pulley and the belt carried thereby is always in alinement with the associated rail. The rear pulleys 58 are not driven, and each pulley 58 is supported from the end of a rail 55 by a bracket 59, into which is threaded the rear screw shaft 59. Each pulley 58 is sup-, ported on a stud 18 that is adjustable within a slot 1| provided by the bracket 59, in order to adjust the tension of each belt 31.

The operating lever 43 for each arm 39 that carries a pull roll 40, provides a hub 12 that is slidably keyed to the shaft 44 that passes freely through the conveyor below the rails 55. Each hub 12 provides a slot 13, in which is received a rail 55, so that when the rails 58 are adjusted by means of the screw shafts 59, the levers 43 are moved with the rails to maintain the rolls 48 in the same relative positions with respect to the belts 31, as previously described with reference to Fig. 3. In other words. any adjustment of the space between the rails is accompanied by corresponding movement of the associated pulleys 51 and 58 and the belt 31 carried thereby, as well as of the lever 43, which pivotally supports the roll 48 that is depended upon to move each blank from the second adhesive applying station to the assembled blanks on the belts.

As best shown in Fig. 13, a series of traction rolls 52 are supported above each belt 31 by a bar 14 extending parallel to and above a rail 55. Each bar is supported at intervals along the conveyor by brackets 15, secured to the under side of a rail 55 and providing studs 15 extending inwardly so as to slightly overhang the associated rail. Each traction roll 52 is rotatably carried by an arm 11 pivotally mounted on a bar 14, and springs 18 acting on the arms 11 yieldably maintain the rolls 52 in engagement with the associated belts 31. Therefore, when the overlapped flaps 2a of an assembled series of envelope blanks are engaged by the traction rolls 52, the rolls exert sufficient pressure to maintain the flaps firmly in engagement with the slowly moving belts 31, so that the assembled envelopes are conveyed between the dryer hoods 53. The fact that one or more blank flaps are engaged by each roll 52, insures that the assembled blanks will travel along the con-' veyor without sagging in the space between the belts where the adhesive bands A and B are exposed to a drying action on opposite sides of the assembly.

Referring again to Fig. 2, the shaft 25 which carries the feed segments 24, is continuously driven from any suitable source of power, not shown, as by means of a sprocket 19. A pinion 51a forming part of the reduction gearing for driving the conveyor pulley shaft 55, is mounted on the shaft 25 adjacent the driving sprocket 19, so that the conveyor belts 31 are driven at a lineal speed considerably less than the peripheral speed of thesegment 24; The shaft 25 also carries a gear 89, which is in mesh with a gear 81 mounted on the shaft 23 which carries the upper set of feed segments 22. The gears 88 and 81 have a one to one ratio, so that the segments 22 and 24 travel at the same speed, although in opposite directions of rotation.

The shaft 23 carries a cam 82 adjacent the gear 81, and this cam 82 is adapted to control pivotal movement of the suction picker 20. The picker 20 is turnable with the shaft 21 that is mounted on the rear side of the cross member 9, as indicated by the broken-away portion, The opposite end of the shaft 2| carries a lever 83, the lower end of which carries a roll 84 bearing on the cam 82. The upper end of the lever 83 is connected to' a spring 85, which as best shown in Fig. 1, tends to hold the roll 84 in engagement with the surface of the cam 82.

With the roll 84 bearing on the high portion of the cam 82, as indicated in Fig. 14, the free end of the pic air 20, shown in dotted lines, will be held in engagement with the lowermost blank of the stack adjacent the stop III, in position will be turned with the shaft 2| under the pull of spring "to flex the end of the blank away from the stop i9, due to suction, which at that time isapplied to the picker.- From the form of the cam 92 indicated in Fig. 14, it is evident that-the picker. 29v will be turned to separate a blank from the stack, just prior to the arrival of the forward ends-22a of segments 22 at the upper end of the stack.

As. indicatedfabove, suction is adapted to be applied to the picker 29, and to this end, a pipe 99 leads from one bearing 91 of the shaft 2|, which is hollow. The other end of the pipe 99 is connected to a block 89 leading to a timing device 99 carried by the frame, and having a rotating element, not shown, turnable withthe gear 9|. The timing-device 99 is so set that suction is applied to the picker 29 over substantially one half of a revolution of the shaft 23;. As indicated by the arrows of Fig. 14, the suction starts substantially one quarter of a revolution in advance of the arrival of the forward ends 22a of the segments 22 at the stack, and is cut off substantially at the same moment that the leading edge of a blank being withdrawn enters the bite of the segments 22 and 24.

A second timing device 99 surrounds the shaft 25 and comprises a rotating element, not shown, turnable with the gear 99, whereby the source of suction is connected once during each revolution of shaft 25 to the cross pipe 21 that extends between the several feed segments 24, in communication with the several slots 29 adjacent the forward ends 24a of the segments. As indicated in Fig. 14, suction is applied to the cross pipe 21 through substantially one half a revolution of the shaft 25, so that suction is present at the slots 29, just before meeting the forward ends 220 of the segments 22. The suction applied to the segments 24 is broken just as the leading edge of the withdrawn blank reaches the stripping fingers 3|, so that the blank is firmly held by the segments 24 until the stripping action begins. Thus the applications of suction to the picker 29 and to the segments 24, slightly overlap in point of time, just before a' blank enters the bite between the segments 22 and 24. a

As best shown in Figs. 2 and 14, the shaft 25 carries a cam 9| beyond the right-hand frame I, with which cooperates a roll 92 carried by a lever 99, freely mounted on an end of the shaft 99 which drives the conveyor pulleys. The lever 991s connected by a link 94 to a similar lever 95, turnable with the shaft 44 carrying the arms 43 which control the position of the rolls 49, as indicated in dotted lines. The cam 9| is so timed that the rolls 49 are adapted to move in quickly to the position shown in Fig. 5, after the clamping arms 45 have operated to engage the leading edge-of the blank that has just arrived at the second adhesive applying bar 29. As the lowermost blank at the bar is pulled out, due to the pressure of the rolls 49 on the belts 31, the cam 9| retracts the rolls 49 to the position of Figs. 6 and 7 where they remain an appreciable period, equivalent to substantially one half of a revolution of the shaft 25. 1

'As previously pointed out, the shaft 25 also carries a cam 5| for controlling the clamping arms 45, the cam 5| being indicated in dotted lines in Fig. 14. From this showing it is evident that the timing of the cams 9| and 5| is such in Fig. 11, opposite to the lever 95.

that e clamping arms 45 will be turned downwardly into the position of Fig. 5, before the rolls 49 move in, and that thisclamping pressure will be maintained on the blank Just stripped until the lowermost blank on the bar 29 has been completely cleared of the trough 34, as shown in 'I3, this condition is always insured as long as there are any blanks in the stack, due to the thereafter arise, wherein the removal of, the

blank last delivered from the bar 29 will leave the trough 34 uncovered. As this would be undesirable, due to possible overflowing of the ad hesive, the invention contemplates means .for automatically preventing movement of, the rollers 49 to the blank withdrawing position of Fig. 5, should the picker 29 fail to deliver a blank to the feed segments 22 and 24.

To this end, the shaft 44, which carries the arms 43, also carries a stop arm 96, which is located outside one of the side frames I, as shown This stop arm 96 swings back and forth as the shaft 44 is turned first in one direction and then the other by the cam 9|, to impart a reciprocatory move-' jects beyond the cylinder 91 into the path of movement of the stop arm 96, as indicated in dotted lines. 91 is connected by a pipe IM to an opening I92 communicating with the inside of the suction picker 29, see Fig. 14. When suction 'is applied to the picker 29, the plunger 99 will-be withdrawn out of the path or movement of the arm 96, as shown in full lines in Fig. 11, due to the admission of air at atmospheric pressure through a s 7 port I93 provided at the opposite end of the cylinder 91.

During the normal operation of the mechanism, suction will be applied to the cylinder 91 throughout the entire period that suction is ap-' plied to the picker 29, so that the end of the plunger 99 is retracted when'the stop arm 95 moves past the cylinder as the shaft 44 turns to move the rolls 49 from the position of Fig. 4 to the position of Fig. 5. At this particular moment, two blanks are in position over the bar 28, and the picker 29 has already swung away from the stack to flex the end of the lowermost blank of the stack into a position where its edge will beseized by the advancing forward ends 22a The opposite end of the cylinder of the segments 22. However, should the picker 20 fall to pull a blank away from the stack as it so moves, the end of the picker will be open, so there will be no suction at the opening I02 leading to the pipe ll.--When this occurs, suction is no longer effective in the cylinder 91 to retract the plunger 98, with the result that the spring I00 pressing on the piston 99, forces the plunger out into the path of movement of the stop arm 96.

Assuming that the lever 85 and arm 96 occupy the dotted line positions of Fig. 14 upon the occurrence of a failure in the blank feed, as described above, it is evident that the shaft 44 will be prevented from turning in a counter clockwise direction, by reason of the engagement 7 of the arm 96 with the projecting end of the plunger 98. Therefore, when the low portion of the cam 9| comes opposite the roll 92 on the lever 93, as shown in full lines, the roll 92 is unable to follow the face of the cam under the pull of the spring 93a, and there is no movement imparted to the pull rolls 40 in the direction of the bar 28 to cause withdrawal of the lowermost blank from beneath the stripping fingers 3|. In this way, the withdrawal of the blank from the bar 28 is automatically prevented until another blank has actually been withdrawn from the stack by the suction picker, thereby insuring that at all times a blank will be in position over the bar 28, so as to be in engagement with the adhesive applying trough 34.

From the foregoing, it is apparent that by the present invention there is provided an improved method and apparatus for applying drysealing adhesive to different and separated areas of envelope blanks, followed by drying of the adhesive from opposite sides of an assembly of overlapping blanks, with the separate adhesive areas positively maintained in spaced relation, so that stringing or edge sticking of adjacent blanks is entirely eliminated. In carrying out the invention, each blank is successively moved in different planes, so as to cause the application of the adhesive with a wiping action, to what constitutes the trailing edge of the blank in each separate movement. In this way, the troublesome problems heretofore encountered in the application of dry-sealing adhesive, are successfully solved, owing to the fact that each application of adhesive to a given blank, is made entirely independently of the application of adhesive to other blanks, and that all the adhesive applications are maintained entirely separate during the drying thereof.

I claim:

1. An improved method of applying adhesive to envelope blanks, which consists in first withdrawing a blank from a supply of blanks while engaged with a supply of adhesive, said withdrawal being accompanied by the application of adhesive to the trailing edge oi. the blank on one side only, then presenting the leading edge of the blank to a second adhesive supply followed by withdrawal of the blank from said second supply, accompanied by application of the adhesive to the trailing edge of the blank on the opposite side, as regards its second withdrawal.

2. The improved method of applying adhesive to envelope blanks, which consists in first withdrawing a blank from a supply of blanks while engaged with a supply of adhesive, with said withdrawal being accompanied by the application of adhesive to the trailing edge of the blank, then 75' presenting the leading edge of the blank to a second adhesive supply followed by withdrawal ofthe blank from said second supply, accompanied by application of the adhesive to the trailing edge of the blank as regards its second withdrawal, and finally in supporting and conveying said blank while subjecting the applications of adhesive to a drying action from opposite sides of the blank.

3. Apparatus for applying adhesive to blanks, comprising in combination, a supply of adhesive, means for supporting a stack of blanks, with the lowermost blank of the stack in engagement with said adhesive supply, a second supply of adhesive, means for maintaining a blank in engagement with said second adhesive supply. means for removing a blank from the first adhesive supply and delivering it to the second, and means operated in timed relation with said first blankremoval means for removing a previously delivered blank from said second adhesive supply.

4. Apparatus for applying adhesive to blanks,

comprising in combination, a supply of adhesive, means for supporting a stack of blanks, with the lowermost blank of the stack in engagement with said adhesive supply, a second supply of adhesive,

means for maintaining a'blank in engagement with said second adhesive supply, means for withdrawing a blank from the stack to cause the application of adhesive from the first supply to the trailing edge thereof, means for delivering said blank to the second adhesive supply. and means for causing the removal of a previously delivered blank from said second supply to apply adhesive to the trailing edge thereof.

5. Apparatus for applying dry-sealing adhesive to blanks, comprising in combination, a supply of adhesive, means for supporting a stack of blanks, with the lowermost blank of the stack in engagement with said adhesive supp a second supply of adhesive, means for maintaining a blank in engagement with said second adhesive supply, means for withdrawing a blank from the stack to cause the application of adhesive from the first supply to the trailing edge thereof, means for delivering said blank to the second adhesive supply, means for causing the removal of a previously delivered blank from said second supply to apply adhesive to the trailing edge thereof, and means for supporting a blank as withdrawn from the second adhesive supply, with the applications of adhesive at different edge thereof exposed to a drying action.

6. Apparatus for applying adhesive to blanks, comprising in combination a supply of adhesive, means for supporting a 'stack of blanks, with the lowermost blank of the stack in engagement with said adhesive supply, a second supply of adhesive, means for maintaining a blank in engagement with said second adhesive supply, means for withdrawing a blank from the stack and the first adhesive supply and delivering it to the second adhesive supply, means for causing the removal of a blank from the second adhesive supply, and. means for preventing the withdrawal of a blank from the second adhesive supply, in advance of the delivery of a blank from the first adhesive supply. Y '7. Apparatus of the class described, comprising in combination, separate sources of adhesive supply, means for maintaining separate blanks in engagement with each such supply, means for transferring a blank from one adhesive supply to the other, means for causing the removal of a blank from the second-named supply, and means bar with a portion thereof engaging said trough along a zone parallel to one edge, but offset therefrom: suction means acting on the edge of the blank to maintainit in engagement with said adhesive trough, and means for withdrawing said blank'froni said bar to cause the applica tion of adhesive upto said edge.

i 9.' In apparatuso'! the class described, a member providing an open trough for receiving a liquid adhesive, means for positioning a blank on said member with a portion thereof engaging said trough along a zone parallel to one edge but offset therefrom, a conveyor for supporting a portion of said blank beyond said member, without imparting movement thereto, and means cooperating with said conveyor to withdraw said blank from said trough and cause the application of adhesive up to said blank edge.

10. In apparatus of the class described, a member providing an open trough for receiving a liquid adhesive, means for positioning a blank on said member with a portion thereof engaging said trough along a zone parallel to one edge but oilset therefrom, 9, conveyor for supporting a portion of said blank beyond said member, without imparting movement thereto, and means cooperating with said conveyor to withdraw said blank from said trough and cause the application of adhesive up to said blank edge, said conveyor being adapted to engage said blank only outside of the zone of application of the adhesive.

11. In apparatus of the class described, a member providing an open trough for receiving a liquid adhesive, means for positioning a blank on said member with a portion thereof engaging said trough along a zone parallel to one edge but offset therefrom, a conveyor for supporting a portion of said blank beyond said member, without imparting movement thereto, and means cooperating with said conveyor to withdraw said blank from said trough and cause the application of adhesive up to said blank edge, said trough being adjustable between its ends to control the length of the adhesive band applied to said blank, and said conveyor being adjustable in width, so as to engage said blank only outside of the extremities of the adhesive band,

12. In apparatus of the class described, a member providing an open trough for receiving liquid adhesive, means for positioning a blank on said member, with an endportion thereof engaging said trough along a zone parallel to one edge but offset therefrom,'said'blank providing side flaps extending beyond its zone of engagement with said member, spaced conveyor belts adapted to engage said side flaps, and means cooperating with said belts and side. flaps to cause. the withdrawal of said blank from saidtrough accompanied by the application of adhesive from said trough in a band extending up to the trailing edge of the blank.

13. In apparatus of the class described, a mem ber providing an open trough for receiving liquid adhesive, means for positioning a blank on said member, with an end portion thereof engaging said trough along a zone parallel to one edge but offset therefrom, said blank providing side flaps extending beyond its zone of engagement with said member, spaced conveyor belts adapted to 7o engage said side flaps, and means cooperating with said belts and side flaps to cause the withdrawal of said blank from said trough accom-' panied by the application of adhesive from said trough in a band extending up to the trailing edge of the blank, said adhesive trough being ad- Justable in length to accommodate blanks of different widths, and said belts being relatively adiustable to vary the space therebetween for engaging the side flaps of blanks of diiferent widths.

14. In apparatus of the class described, a member providing an open trough for receiving liquid adhesive, means for delivering a blank edgewise to said member, means for stripping said blankfrom said delivery means, and positioning the blank on said member with an end portion thereof engaging said trough along a zone parallel to one edge but ofiset therefrom, and suction means acting on the edge of the blank to maintain it in engagement with said adhesive trough, whereby withdrawal of said blank from said-bar causes the application of adhesive up. to said edge.

15. .In apparatus of the class described, a member providing an open trough for receiving liquid adhesive, means for delivering a blank edgewise to said member, means for stripping said blank from said delivery means, and positioning the blank on said member with an end portion thereof engaging said trough along a zone parallel to one edge but ofiset therefrom, suction means acting on the edge of the blank to maintain it in engagement with said adhesive trough, whereby withdrawal of said blank from said bar causes the application of adhesive up to said edge, and means for maintaining a. second blank in register with the trough above the blank being withdrawn, whereby withdrawal of the lowermost blank is accompanied by progressive engagement of the upper blank with said suction means and trough.

16. In apparatus of the class described, a member providing an open trough for receiving liquid adhesive, means for successively delivering blanks edgewise to said member, means for stripping blanks from said delivery means to position blanks in overlying relation above said member, with a portion of the lowermost'blank engaging .said trough along a zone parallel to one edge, but

ofiset therefrom, means for withdrawing said blank from said trough to cause the application of adhesive up to its edge, and means co-operating with said member to prevent the uppermost blank from being withdrawn.

17. In apparatus of the class described, a member providing an open trough for receiving liquid adhesive, means for successively delivering blanks edgewise to said member, means for stripping blanks from said delivery means to position blanks in overlying relation'above said member, with a portion of the lowermostblank engaging said trough along a zone parallel to one edge, but ofiset therefrom, means for withdrawing said lowermost blank from said trough to cause the application of adhesive up to its edge,- and means for maintaining the edge of the uppermost blank in register with said trough during withdrawal of the lowermost blank, whereby saidwithdrawal is accompanied by progressive-engagement of the uppermost blank with said trough.

18. In apparatus of the class described, a member providing an open trough for receiving liquid adhesive, means for successively delivering blanks edgewise to said member, means for strippingsaid trough along a zone parallel to one edge, but oflset therefrom, means for withdrawing said lowermost blank from said trough to cause the application of adhesive up to its edge, conveying means for partially supporting only the lower one of two overlying blanks while in register with said bar, without imparting movement thereto, means cooperating with said conveying means to cause the withdrawal of said blank from said trough, accompanied by the application of adhesive up to its edge, and means operating on the uppermost blank to hold it in register with said trough and out of contact with said conveying means, while said withdrawal is being accomplished.

19. An improved method of applying dry-sealing adhesive to envelope blanks, which consists in supporting a blank with an edge portion thereof held in engagement with a supply of dry-sealing adhesive extending parallel to said blank edge portion, moving a second blank into overlying relation to the first blank with an edge portion thereof alined with the edge portion of the first blankj and then withdrawing said first blank from said adhesive supply to cause the application of r adhesive up to the trailing edge thereof, accomthereof alined with the edge portion of the first blank, and then withdrawing said first blank from said adhesive supply to cause the application of adhesive up to the trailing edge thereof, while maintaining aiinement of the edge portion of said second blank with the adhesive supply, as the go first blank is withdrawn. 

